


Light in the Tunnels

by CatKing_Catkin



Series: The Rising Up of the Underworld [2]
Category: Undertale (Video Game)
Genre: Acts of Kindness, Alternate Universe - Underfell, Ambiguous/Open Ending, Brother Feels, Brotherhood, Brotherly Love, Developing Friendships, Developing Relationship, Dismemberment, Dysfunctional Family, Dysfunctional Relationships, Gen, Hanging, Implied Cannibalism, Implied/Referenced Torture, Papyrus Has Issues, Papyrus Needs A Hug, Protective Grillby, Protective Papyrus, Reconciliation, Redemption, Rescue Missions, Roadtrip, Sans Doesn't Remember Resets, Sans Has Issues, Sans Needs A Hug, Sequel, Suicidal Thoughts, Underfell Grillby, Underfell Papyrus, Underfell Sans
Language: English
Status: Completed
Published: 2016-07-26
Updated: 2016-07-29
Packaged: 2018-07-26 22:56:23
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 11,661
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7593613
Author URL: https://archiveofourown.org/users/CatKing_Catkin/pseuds/CatKing_Catkin
Summary: <blockquote class="userstuff">
              <p>Sequel to "Line in the Snow"</p><p>Frisk managed to talk Papyrus into letting them flee Snowdin, and into giving his brother another chance while he was at it. But when the brothers return to town, cold reality sets in - the rest of the Snowdin Guard aren't so willing to accept that as an excuse for failure. It takes everything the two skeletons have just to survive the punishment that follows, and to form a plan about where to go from there. </p><p>Papyrus turns out to have some very definite ideas for new directions the Underground might take. And he's more than willing to drag his brother along this time so they can see those changes together. Sans is just happy to have a place by Papyrus' side again, and he finds himself getting creative to make sure he can stay there.</p>
            </blockquote>





	1. Cold Reality

**Author's Note:**

> So I'm aware that I left "Line in the Snow" with a very open ending. But my mind just wouldn't leave it there. I kept coming back to the fact that even though it was an *open* ending, all implications pointed to it being not necessarily a *happy* ending. I kept thinking about the shitstorm that would be waiting for Papyrus and Sans once they got home, and how they might deal with it. And then my natural prediliction for whump kind of handled the rest.
> 
> Underfell is not easy for me to write, sequels in general even less so, but the relationship I'm building between UF!Sans and UF!Papyrus actually is. So I'm pretty happy with the results here. Hopefully you are, too.

The dogs were waiting for them, when they got back to the house.

Papyrus obviously noticed them before Sans did. It was the way his brother paused for just a second that made Sans look up again in the first place. Sure enough, he could pick out the silhouettes in the distance, all gathered around their house – Doggo, the Dogi, and Greater Dog. Lesser Dog was probably off losing blackjack against itself, but that only marginally improved the situation. Even at this distance, Sans could see something _expectant_ about them, in their stance and in their souls. Something predatory.

They were Papyrus’ soldiers, of course, and he’d trained them to be vicious and predatory. But they were only Papyrus’ soldiers because he was the head of this division of the Royal Guard. Not only that, but he was strong enough to beat down anyone who disagreed with the idea.

Yet everything had changed now. Papyrus had obviously not captured the human, had obviously not killed the human. More than that, he was carrying Sans in his arms, and all of Snowdin knew that Papyrus normally treated his brother with irritation and disdain. Sans had been glad to see that return of weakness out by the river, brought out by Frisk’s kindness. But now it was as though they’d returned to the real world, awoken from a pleasant dream. Now he could see the consequences looming.

The Underground was not a place where weakness thrived.

He half expected Papyrus to come to his senses, to drop him back into the snow again. Papyrus didn’t. “you maybe wanna put me down, bro?” Sans murmured to him, while they were still far enough away to not be overheard. Just in case his brother had forgotten he was carrying Sans in the first place.

“NO,” said Papyrus, and that was that.

The dogs looked to one another as their captain drew near, and Sans heard them barking and yapping amongst themselves. Eventually, it was Dogaressa who was chosen to step forward, though Dogamy was as ever at her shoulder.

“What happened, Papyrus?” she asked. One paw was already resting on the haft of her axe.

“THE HUMAN ESCAPED,” said Papyrus simply.

Dogamy let out a huff. “How? They were barely outside the gates when we realized what had happened. And their only ally was…” He jerked a snout at Sans. “ _That_.”

Sans heard Papyrus grind his teeth for a moment. “IF CAPTURING A HUMAN WAS EASY, THEN WE WOULD ALREADY BE OUT FROM UNDER THIS DAMN MOUNTAIN.”

“I don’t understand,” said Doggo. “Where is Sans?”

“In his dear brother’s arms,” Dogaressa sneered. “How _sweet_.”

Sans realized just then _why_ he was still in Papyrus’ arms. He didn’t move much at the best of times. Now, like this, he was all but invisible to one of the dogs. It was something. It was an edge. He didn’t know if it would be enough.

Papyrus, on the other hand, continued to seem unfazed. He stood tall and unflinching, regarding the dogs with his habitual disdain. “WHAT, PRECISELY, DO ANY OF YOU MUTTS WANT? WHY ARE YOU LOITERING OUTSIDE MY HOUSE INSTEAD OF OUT ON PATROL? AT LEAST _I_ WENT OUT TO TRY AND CAPTURE THE HUMAN.”

Dogaressa nodded slowly. “That’s true…you did…”

“Maybe he could have done it,” Dogamy added. His eyes narrowed. His teeth gleamed a little in the faint light. “But Sans is _always_ in the way.”

Doggo whuffed in agreement. “Sans is always where he’s _not wanted_.”

Dogaressa took a step forward. Papyrus didn’t take a step back. “Is _that_ why you’re allowing this pathetic little display, Captain? Did Sans not want to take his medicine any other way?”

“Hand him over,” Dogamy continued. He started to draw his axe. “We’ll fix that.”

Sans felt a chill race up his spine as Papyrus really did move to set him down on the ground. But in the next moment, he realized that he was being given a second to get his feet under him. It was a second he took, and once he had, he found himself forcibly shoved _behind_ Papyrus. Protected, and visibly so.

The dogs barely had time to register that much before they were all dragged down forcibly to the snow, souls turned blue. Dogamy hit the hardest. Greater Dog, on the other hand, almost managed to keep his feet. He had slumped to his knees but had braced one paw in the snow to keep from slumping further. He looked up at Papyrus, glaring ferociously, and started to growl.

The other dogs took up the growl, a rolling tide of malice that washed over the two skeletons and promised violence to follow.

“RUN,” said Papyrus to Sans.

Sans wanted to. He wanted so much to run from this place and never look back. But only if his brother was with him. “nuh-uh,” he replied, shaking his head.

“THAT WASN’T A _REQUEST_ , SANS. IT WAS AN ORDER. I _AM_ STILL THE CAPTAIN OF THE SNOWDIN GUARD.”

“i kinda think they’d like to talk with you about that, bro.”

Sure enough, all the dogs were now struggling back to their feet. Sans could see Papyrus starting to sweat with the effort of keeping them all down. He wouldn’t be able to keep it up for long.

Papyrus still scoffed, as though this were the easiest thing in the world. “THESE MUTTS? _PAH._ ALL I NEED TO DO IS GIVE THEM ALL A GOOD SWAT, AND THEY’LL FALL WHIMPERING BACK INTO LINE. JUST LIKE ALWAYS.”

“their bark is worse than their bite, huh, bro?”

Papyrus groaned aloud, and Sans couldn’t help but smile a little. “SANS, HONESTLY! NOW IS NOT THE TIME FOR YOUR HORRIBLE JOKES! NOW IS THE TIME FOR YOU TO BE RUNNING AWAY!”

“i want to help.” Sans summoned a pair of blasters, one over each shoulder, turned towards the dogs with gaping jaws. “how many times have i ever said that? and i _can_ help.”

“RIGHT UP UNTIL THE POINT ONE OF THEM KILLS YOU. HOW MUCH HP DO YOU _HAVE_ SANS? CAN YOU DODGE THEM ALL AT ONCE?”

Sans hesitated. He didn’t know. The blasters flickered, and the Dogi took their chance.

Snarling, they lunged – Dogaressa went high, and Dogamy went low. A terror seized Sans at the sight of those gleaming fangs and bloodthirsty eyes, a terror that made him close his eyes and flinch away as he wildly directed the blasters to fire. He heard the clash of metal on bone a scant second before he heard Dogamy yelp as the blast connected with him. “SANS!” he heard Papyrus yell, and Sans opened his eyes just enough to dodge out of the way of a slash from Greater Dog’s spear. But then he felt the air displaced behind him and turned in time to see Dogaressa’s axe arcing down for his skull, and Sans knew the answer too late, he couldn’t dodge three at once…

Sans felt an impact, but it was one that sent him staggering to the side, staggering clear. The next thing he heard was Papyrus crying out in pain as the axe bit deep into his shoulder. Sans brought himself some time by firing the blasters to his left and right, but he didn’t look to see whether they hit their mark. He looked up instead to his brother, who was still clashing bone to-to-axe with Dogaressa.

“RUN, YOU IDIOT!” Papyrus barked, risking a glance back at Sans. It was a risk that nearly led to him getting his head taken off as Dogamy came to his wife’s aid. Papyrus pivoted on the spot, breaking the deadlock and almost leading to the two dogs knocking their skulls together, and he stabbed out with his staff to catch Dogamy a hard blow to the gut.

Papyrus could fight. Papyrus really was stronger than any of them. Sans had his tricks, of course, but Sans wasn’t used to fighting anymore. Papyrus could take more than one hit, and Papyrus was showing that he _would_ take more than one hit if it would keep Sans from taking a hit at all.

Surrounded by flying fur and the sound of snapping teeth and clashing weapons, Sans realized the cold, hard truth of the matter – he was a liability, and maybe always had been.

“please don’t die,” he heard himself say, as though a stranger spoke those heartfelt words. He waited, even if it meant dodging another blow from Dogamy, until he saw Papyrus nod.

Then Sans vanished, and didn’t reappear within the bounds of Snowdin.

When the world came back into focus, he was surrounded by the tall trees of the forest, and all was silent but the wind.

*  *  *

He considered going back through the woods, towards the big doors that never opened. Towards his, for lack of a better word, “friend” who lived in the Ruins. Maybe this time, she would open the doors to him. Maybe he could hide away with her and never have to face this world again, and maybe she wasn’t as unhinged in person as she sometimes sounded.

Sans went forward, instead – back towards Snowdin. Maybe he would only find his brother’s dust to greet him. But at least if he did, one monster could ensure he got a proper funeral.

Such was the world they lived in, and Sans _hated_ every inch of it.

He hated himself even more for being too much of a coward to keep it from going on.

At least the teenagers who lived here really were a matter of bark over bite, posturing over violence. Some rumors had it that this was the reason they lived in the woods in the first place, because they were too weak to cut it against the rest of the Underground. Others whispered that they had been banished to the forest for being too violent even for most monsters, that the things they did to those they captured in the dark would disgust the King himself.

Sans didn’t really care to find out, either way. It was probably safe to say that he’d been pretty well fired from his job as a sentry around about the time he’d hurried out of Snowdin alongside Frisk. So he wasn’t really obligated to care anymore.

Time to move on.

He didn’t take a shortcut back to town, though. He didn’t know the sight that would greet him when he did, and it always took him a second or two to get his bearings back after making such a leap. A second or two would be all a loyal citizen needed to finish the job, if the wrong person was waiting for him.

So Sans walked, instead, no matter how tedious or tiresome a journey it was. He walked, and deliberately didn’t look around at the occasional patter of snow from the trees or the crunch of it underfoot from someone he couldn’t see. Only once did he pause, when he felt a presence right over his head, felt the pulse of menace and hostility closing in. Only once did he take a deep breath and risk calling out: “i’m not here to hurt anyone.”

Then he slid forward along a patch of ice and didn’t wait to see if anyone had heard him. But the sounds of being followed were less frequent, after that, and faded entirely as he got near the bridge. Maybe they’d listened. Maybe they just didn’t want to risk harassing a guard, even now, even a guard as weak as him. Sans resolutely continued not to care, either way.

He did stop for a little while, when he reached the bridge. He stopped and settled down in the shadow of a larger boulder, there to doze for a while until the deeper darkness of night fell. It itched at him, to wait like this, to leave his brother like this. With more practice than he would have liked, Sans tamped that worry down. If Papyrus was going to die, he would already be dead. If he had managed to get away – _he has to have gotten away_ – then it would be stupid to invalidate all his hard work protecting Sans by getting himself killed anyway.

At least between the woods and the bridge, it was all open ground. He’d hear anyone coming long before they did anything.

He hoped as much, at least.

But with nothing else to go on, Sans closed his eyes and quickly fell into a doze.

*  *  *

He woke to the sounds of distant laughter.

Sans didn’t immediately give any sign that he was awake, of course, not until he was sure that it really _was_ distant laughter. Finally, he decided that it must be coming from near the western gate of Snowdin, which was unfortunately right where he needed to go. Even if his ultimate intention was to creep around the wall towards the eastern gate, there was no good way to do that without passing at least briefly in sight of the gate on this side.

He risked peeking around his hiding place and down along the bridge. The sight that greeted him was just as bad as he’d thought, and even stranger to boot. All the guard dogs were clustered around the gate, and as they talked and laughed with each other they seemed to be hoisting something over the gate, there to hang like a sack of old laundry. Or maybe a scarecrow, to keep the mysterious teenagers away. Yes, a scarecrow, that was what it had to be.

Then Sans caught a flash of red armor from the lights of the distant town, and felt so dizzy with horror that he slumped back against the rock. His brother. _They were hanging his brother_. 

Sans struggled to breathe and tried not to rattle in shock. Any failures to do so on his part fortunately still weren’t loud enough to be heard over the dogs’ jeering. Slowly, too slowly, he managed to claw bits and pieces of rationality back together.

Papyrus was alive. Probably unconscious, if the lack of shouting was anything to go by, but in one piece. Hanging wouldn’t finish him off. They didn’t _need_ to breathe. It was a pleasant feeling, and the feel of fresh air moving through your skull could help you get your bearings back. But it wasn’t actually _required_. A rope around the neck probably couldn’t even stop them from breathing anyway. Probably, at least – he’d never been in a position to find out. Either way, Papyrus was alive, the guards were keeping him alive just a little longer even if only to humiliate him. That was fine. It gave them time.

Sans resolved to wait five minutes. Fortunately, luck was finally with him and the guards left after another three. He heard their voices retreating, but didn’t hear the gates closing. Obviously, they wanted their disgraced former commander to be seen. But whether he was seen or not, silence returned after they were gone.

Sans screwed his eyesockets shut. He took a deep breath.

Then he rolled out from behind the rock, stared down the bridge, and took a hasty shortcut into the deeper shadows beside the gate. He furiously blinked the world back into focus after doing so, and the first thing he looked around for was his brother. Sans felt his soul grow warm with relief to see that Papyrus _was_ awake, _was_ trying to work at the rope around his neck.

And then it felt like he’d just fallen into an icy river, when he realized one particular detail that was giving Papyrus a lot of trouble in that attempt.

“your arm…”

Papyrus froze. Sans heard his breath catch.

“WHAT ABOUT IT?” his brother finally asked, stubborn as ever. But he wasn’t stubborn enough to keep the notes of pain out of his voice.

Sans, for his part, didn’t even bother to try and hide the horror in his. “it’s _gone_.”

“YES, SANS. VERY ASTUTE.” Papyrus lifted his remaining arm to try again to work at the rope. “I TOLD YOU TO RUN, BY THE WAY.”

“yeah, you did. didn’t say where to.”

“I DIDN’T THINK I HAD TO SPECIFY!”

Sans winced as his brother’s affronted yowl cut through the otherwise quiet night. “yeah, well, you did. so i’m thinking we, um, maybe make a break for waterfall? after i get you down. and maybe after you take a deep breath and _chill_ the hell out. i kinda wanna get you down without the dogs coming back, y’know?”

He apparently made a sufficiently convincing point. Papyrus subsided, grumbling, and Sans considered his options. He tried to ignore how dire those options must be, if Papyrus had even ignored such an obvious pun.

Finally, he took a quick shortcut up to the top of the gate, immediately crouching down as low against the wood as he could once he reoriented himself. Hopefully, no one would think to look up and notice a slightly different shadow when Papyrus himself was making such a visible sight. Then Sans went to work slowly easing himself over to the beam supporting his brother’s weight. He slid his fingers carefully over the wood, searching for the rope.

_“damn.”_

“WHAT?”

“that’s, uh…that’s not a rope holding you up, is it?”

“YES, _THANK YOU_ , SANS! I HADN’T NOTICED!”

It was a wire. Sans had to swallow down the urge to giggle hysterically. He managed it, just barely, and set to work trying to undo the knot in the wire instead. “man,” he heard himself babbling as he scrabbled at it. “we should have just gone with frisk. we should have just blown this mean cream stand and gone with the kid.”

“I, UNLIKE YOU, STILL TOOK MY RESPONSIBILITIES SERIOUSLY! UNLIKE YOU, AND UNLIKE THOSE _FLEABITTEN MONGRELS_!”

“oh, yeah? and how’s that workin’ out for you? seems to me like you went _barking_ up the wrong tree, bro.”

“I HATE YOU.”

“i know,” Sans replied glumly.

The wire was thin and fine, the sort of thing you’d find in a piano. Worse still, up here he had next to no light to work with. Sans struggled with it for a moment, anyway. He first tried to find the knot, and then tried to work it undone, until at last a stab of pain shot through his palm and he winced.

“WHAT HAPPENED?” Papyrus asked immediately.

“nothing,” Sans replied, just as immediately, before trying to wipe his bleeding palm on the beam. “look, i can pull you up. but, uh, somebody’s gonna notice pretty quick, and you’re still not going anywhere until we get this leash off.”

“THEN _GET IT OFF OF ME_!”

“i _can’t_!” Sans snapped back, feeling his temper fray in a way the wire was stubbornly refusing to do so. “not without something with an edge. unless you want me to try chewing through it, _boss_.”

For a wild moment, he wondered if Papyrus really would demand just that. It was this doubt, combined with the creeping terror that came with the risk of being caught at any second, that gave Sans the courage to raise his voice towards his brother. Once he realized that he’d done so, he wondered just what was wrong with him. Before today, it would have been a minor miracle if he could even look Papyrus in the eye.

“WHAT PLAN DO YOU HAVE TO ACQUIRE SOMETHING WITH AN ‘EDGE’, THEN?” his brother finally asked, more quietly.

Sans let out his breath in a long sigh. “couple of ideas, actually,” he said. “but, uh, they’d both require leaving you for a bit. you okay with that?”

“I FAIL TO SEE HOW EITHER OF US HAS A CHOICE.”

That was probably true. “okay.” He glanced over his shoulder, back down the road into town and towards his destination. Before he could entirely stop it, Sans found himself whispering: “sorry.”

Papyrus still heard him. “FOR WHAT?” he asked, sounding genuinely curious.

Sans didn’t really know where to start. So he didn’t. He just took a quick shortcut off the bridge and into town.


	2. Run Ragged

When the world reappeared, he was out behind Grillby’s. Sans immediately slumped to his knees in the snow, because the world being back in focus didn’t seem to have stopped it from _spinning_.

Papyrus’ question from earlier returned to him. _How much HP do you even have?_

Normally, of course, the answer was one. Right now, he was still hovering somewhere around two-tenths of a point. He’d never had the chance to heal from his earlier battle with his brother. The dogs had put quite the kibosh on that plan.

Finally, Sans managed to drag himself back to his feet and stumble towards the kitchen door. He paused for a moment to listen for any noise inside. What he heard didn’t point to there being any more than one monster at work back there, and so Sans went to work hammering on the door. “grillby! hey, grillby, c’mon! _please!”_

He wondered if Grillby couldn’t hear him. He wondered if Grillby might ignore him or, worse, he wondered if Grillby might recognize his voice even from out here and go alert a guard instead. He wondered at a dozen different possible worst case scenarios, and then the door was opened so forcefully that Sans almost fell flat on his face onto the floor inside. 

“ _What?!”_ Grillby snarled, looming over him with a sizzling frying pan clenched tight in one hand. “ _What the hell is the matter with…oh. Hey, Ketchup._ ”

The dawning recognition was not immediately followed by death or shouting for the guards. Sans decided to take that as a hopeful sign.

“hey, grillby,” he said, looking up at his friend. He couldn’t immediately discern any expression on his friend’s face, and so risked carrying on: “it’s, uh…it’s been a hell of a day. we kinda need your help.”

_“What you need is to leave. I’ll let you have a head start.”_

And indeed, over the sounds of fries frying and burgers grilling, Sans could hear barks and yips coming through the door at the other end of the kitchen. If Grillby really _did_ want to turn Sans in, he wouldn’t even have to shout very loud.

A chill raced down Sans’ spine, despite the heat of the kitchen. “please don’t,” he said, nowhere close to too proud to beg.

Grillby let out a long, tired sigh, pressing his free hand against his forehead. _“I don’t exactly have a choice, Sans. All it’ll take is one of those mutts catching half a whiff of you in here and they’ll know we talked. What the hell do you think they’d do to_ me _if I didn’t say anything?”_

He made a point. He was, in fact, making exactly the point Sans had been afraid he’d make. But he hadn’t made the only sensible move _yet_. He was giving Sans a chance to talk. It was a dance they’d danced so many times before. _Give me a reason_. That was all it took, with Grillby. _Give me a reason to let you stay after closing. Give me a reason to let you walk_.

“we just need to get out of town. we won’t come back, what do we even have to come back to anymore?”

_“You think they’d risk letting the former captain hook up with a human?”_

“we wouldn’t do that,” Sans lied.

_“Why not? You let ‘em go to start with.”_

“sure, because they’re probably dead already.”

_“They won’t want to risk it. Neither will Asgore.”_

“we didn’t even _do_ anything! they hurt us more than the human did! now they’ve got my brother hanging on the gate like a candycane. i can’t just _leave_ him there. and if there wasn’t some small part of you that agreed with me, you’d already have dragged me out there!”

They stared at each other for a long, breathless moment. Grillby stood tall and distant, still holding the frying pan like he was braced to have to swing it. Sans remained on his hands and knees on the kitchen floor, staring undisguised and unashamed pleading up at perhaps his only friend.

At last, Grillby sighed, and turned away.

 _“Honestly? Sure I agree with you. But I also don’t want to die. Ideals aren’t worth my life. You know the rules, Sans, just as much as I do.”_ He glanced back with shadowed eyes, before he started for the door. _“‘Kill or be killed.’”_

Panic drove Sans on to say what he did next. Looking back, however, he would realize that they were the only words that could possibly have saved him at that moment.

“you can have the house!”

Grillby froze, his hand on the doorknob. He looked back at Sans once more, and asked in a very thoughtful tone of voice: _“What was that?”_

“the house. you can have it. you know the house, right? on the edge of Snowdin? probably the biggest single house in town? it’s _yours_ , if you just give me some supplies. and a knife.”

 _“‘Mine’_ , _huh? For how long?”_

“how long do you _think?_ for good, of course! you really think we’re ever coming back here?”

_“…you’d be idiots if you did.”_

At last, at long, long last, Grillby lowered his hand from the doorknob. He turned back to face Sans, and moved away from the door. Even when he picked Sans up by the back of his jacket and dragged him towards the open back door, Sans couldn’t feel anything but pathetic relief.

Grillby dumped him unceremoniously back into the snow, and held out his hand. _“Key.”_

Sans half-reached towards his pocket, and then hesitated. “food first.”

_“Key first.”_

“knife first?”

Grillby considered this for a moment, and then nodded. He ducked back into the kitchen and returned with a wickedly sharp looking utility knife, which he tossed in the snow at Sans’ feet. _“What for?”_

“does it matter?” Sans picked up the knife and stuck it in a pocket of his coat. “we’ll be back in a few for the rest.” From another pocket, he fished out his house-key and tossed it into Grillby’s waiting hand.

_“You’d better not take long.”_

Sans didn’t intend to. There was no point in keeping secrets any longer, either. He simply took another shortcut away from Grillby’s and back to Papyrus right then and there.

*  *  *

Of course, he almost fell off the gate as a fresh wave of exhaustion swept over him. What snapped him fully back to lucidity was the sound of Papyrus’ voice. “…SANS? IS THAT YOU?”

He sounded almost cautious. Except Sans realized it wasn’t quite that – he sounded _surprised_. Surprised that Sans had come back. He couldn’t have been gone that long, had he? Did Papyrus really still have that little faith in him?

The thought came with less pain than it usually did, this time. In fact, the taste in his mouth was something like pity.

“yeah, bro,” Sans called down. “it’s me. i, uh…” He closed his eyes, took a deep breath, and clenched his hand tight in a vain attempt to stop it from shaking. “i don’t think i have the juice left to pull you up. so it’s gonna be a bit of a drop from here. you ready?”

The wire creaked a little. “YES,” said Papyrus. “I’M READY.”

Sans pulled out the knife and went to work with a renewed vigor. Fortunately, with the knife’s serrated blade, the work only took a moment before the wire snapped with a faint “twang”. Papyrus admirably kept back any sound as he fell for the snow a good ten feet below, even if he landed quite gracelessly without both arms to balance him.

Taking a shortcut down to the ground or just letting himself fall from here would have the same result either way – that result being Sans collapsed in an equally ungainly heap. So he simply peered over the edge, picked out a likely looking snowdrift by the edge of the path, and rolled himself off.

He landed even more softly than he’d hoped for, especially considering that he didn’t land in the snowdrift. It wasn’t until he was being set on his feet that Sans realized where he’d landed instead, and the warmth in his soul was as good as a bottle of ketchup.

Though that brief relief faltered badly when he took his first proper look up at his brother. Up close, it was clear that ripping an arm off wasn’t all that the dogs had done. Cracks spiderwebbed through Papyrus’ skull, and the way he stood made it clear that he was obviously trying not to favor some broken ribs. Other bones were probably bruised at least. But he could still stand, and that had to count for something.

“any idea where your arm _is_?” he asked, not holding out much hope.

“NO. IT DOESN’T MATTER.” Papyrus drew himself up a little more. “I WON’T GET TAKEN BY SURPRISE AGAIN, AND SO I DON’T EVEN _NEED_ BOTH ARMS. IT WAS MY BAD ARM, ANYWAY!”

“heh.” Sans managed to smile. “i know.” He looked down at himself, and then looked back up at the taller skeleton. “carrying our gear’s gonna be kind of tricky, though.” At least assuming that Grillby had even kept to his word, now that he had his payment in hand.

“WHAT GEAR?”

“i think i managed to talk grillby into making us some food for the road.”

“DID YOU? AND HOW DID YOU MANAGE THAT, SANS?”

“does it matter?”

Papyrus gave this all due consideration…and then he half-shrugged. “ADMITTEDLY, IT PROBABLY DOESN’T.”

“right. now, i know this is your second least favorite thing in the world…” Sans was guessing that Papyrus’ least favorite thing in the world now was hanging by the neck from the Snowdin gates by a length of wire. “but do me a favor and _try_ to be stealthy here, bro?”

Papyrus scoffed. “HONESTLY, SANS! THE ONLY REASON YOU’VE NEVER SEEN ME BE STEALTHY IS BECAUSE I’VE NEVER _NEEDED_ TO BE STEALTHY! BUT OUT OF CONSIDERATION FOR YOU, I WILL BE SO QUIET THAT YOU MIGHT EVEN LOSE TRACK OF ME!”

“good deal. let’s see about that.”

Side-by-side with his brother, his senses alight at every step for something to go wrong, Sans crept back into Snowdin alongside his brother for what he hoped would be the very last time.

*  *  *

They didn’t go entirely unseen. Sans was sorry about that. Even now, none of the individual monsters in Snowdin deserved to have the wrath of the guards falling down on their heads. And that would happen, once they realized that Sans and Papyrus had sneaked deeper into the Underground right under their collective noses. They would shake down attempted witnesses, they would get rough. Sans was sorry about that. He could only hope that them not hanging around would mean that any such difficulty wouldn’t last long.

He had to take care of himself. He had to take care of his brother. He had to find the kid. If he narrowed his world down to just those three important details, Sans thought he might just make it.

They made it into town and around to the back of Grillby’s. The door was shut, and for a moment Sans feared the worst. But then Papyrus went to work brushing some snow away from a drift by the wall that hadn’t been there before, and it turned out that no less than three bulging knapsacks had been hidden beneath that snow.

“…how are we gonna carry those?” Sans asked. It probably wasn’t the best thought to have, in that moment, but it was the first one he had anyway.

“HOWEVER WE CAN,” said Papyrus stubbornly. “HELP ME WITH THIS.”

Fortunately, with a bit of work Sans was able to help Papyrus get one of the packs around his remaining arm, with the other strap hooked on a spike on his armor. Sans heaved another one onto his back, and after giving the remaining pack a long, hard look, he cut the straps with his new knife and managed to just about tie them around Papyrus’ waist.

“i think that’s the best we’re gonna get, bro.”

“UNFORTUNATELY, I THINK YOU’RE RIGHT.”

“on we go, then?”

“THERE’S CERTAINLY NOTHING LEFT FOR US HERE. BESIDES _REVENGE_.”

“yeah, well, that’s the thing about revenge, papyrus. it _keeps_.”

Papyrus grinned, and it seemed to Sans that the red pinpricks of light in his eyesockets glowed rather more brightly. “THAT IT DOES.”

Fortunately, Papyrus was willing to let it keep for another day. So equipped for the trek into Waterfall, the two brothers hastened back around Grillby’s and towards the nearest entrance to the town’s underground tunnels. The few monsters that were still out and about after the violence of the day scattered when they saw the skeletons racing down the street. Sans directed a few thoughts of apology towards them, but didn’t slow down.

It soon proved to be a very good thing that he didn’t. Sans faintly heard a door opening in the increasing distance behind him, and only realized the significance of hearing that when he heard the _howl_ start up.

 _“DAMN IT,”_ Papyrus swore. Sans couldn’t have put it better himself, and that was all for the best, because he was so exhausted by now that he couldn’t even have drawn breath to speak. He was already stumbling and panting by the time they drew up to the tunnel, and even the sound of many paws racing nearer couldn’t give him more energy to move more quickly. He didn’t remember dropping down into the tunnels, but that was because Papyrus pulled him down into the darkness.

“ _MOVE!”_ his brother snarled, and Sans _tried_. At least down here, he could ignore the fact that his vision was swimming. At least down here, all he had to do was go forward, there was nothing else to see but the distant light at the end of the tunnel. But the pack was heavy and he was so tired and would it really be so bad if the dogs caught up to him? Papyrus could get away, but Sans would never last in Waterfall, Sans had lasted longer than he even had a right to beneath this nightmare of a mountain.

“SANS, _I FORBID YOU TO DIE!_ THAT IS AN _ORDER!_ ”

Those words were the last thing he remembered hearing for a long while. Sans must have managed to keep running, though. When he came back to his senses, a cold wind was howling, and he and Papyrus were staggering along towards the place where the shadow of Snowdin’s city gates ended.

“what happened…?” Sans mumbled, stumbling almost immediately.

Papyrus reached down and heaved him forward roughly by a hand around his shoulder. “YOU DIDN’T DIE,” he said, and sounded…almost proud? “WELL DONE.”

 _I don’t remember how I managed that_ , Sans wanted to say. Then he wondered if he really wanted to know, and finally decided that he didn’t. “thanks,” he managed, instead, and Papyrus nodded in reply.

They weren’t being pursued. That much became slowly obvious. There were no footsteps audible over the howling wind besides those belonging to the two skeletons. Had they wanted to pursue, the dogs could easily have caught up with Sans and Papyrus given the pitiful pace they were setting. Perhaps they had simply decided to give up the chase, upon seeing that all the brothers really wanted was to leave town. Perhaps they had decided, much like Papyrus had with regards to Frisk, that it would simply be more efficient to leave their punishment to Waterfall.

Dark and hungry things dwelled there. Life in Snowdin could be rough and cruel, but at least Grillby’s threats to cook you up for the dinner rush were _probably_ only threats. Everyone knew that weak monsters that ventured too deeply into Waterfall exited again only as bones carried on the tides.

Sans darted a glance up at his brother, as they limped along side-by-side, and reflected on how the two of them had never looked weaker. Papyrus had to know as much, but Papyrus said nothing about it, and so neither did Sans.

He drifted into a sort of fugue state again as they made their slow and unsteady way down the road. It was easier if he didn’t think too much, if he just went away inside his skull so he didn’t have to feel too much. If he just left his hindbrain in control, the part of him that snapped to attention without thinking whenever Papyrus barked an order, the part of him that instinctively moved to react to his brother’s touch, Sans could just about keep up.

The air grew colder, the already-faint light of the Underground grew darker as they approached the entrance into Waterfall. The river on their left grew slow and, just for a little while, shallow. That thought pierced the fog in Sans’ head before anything else did. _Shallow_. It took him a little while longer, a few more agonizing yards, before he understood why that mattered.

“bro…bro, w-we should stop here. for a break.”

“HAH…EXHAUSTED ALREADY…HUFF…ARE YOU, SANS?”

“yeah.” The time for pride was long since passed, if it had ever been here at all. “you know me, papyrus. way too weak to get too far.”

“WELL…HUFF…I SUPPOSE THIS IS AS GOOD A PLACE AS ANY TO REST. AS STRONG AS I AM, IT’S NOT AS THOUGH I CAN CARRY YOU _AND_ ALL OF OUR SUPPLIES.”

“don’t worry, bro. i won’t tell anyone.”

“NYEH-HEH-HEH…”

Somehow, that weary but unmistakably genuine chuckle from his brother was the most beautiful sound Sans had heard all night. He grinned despite himself.

And he didn’t bother to explain that the reason this was an even better place than any was because the water was shallow. If they slept, they would be safe from big and nasty creatures reaching out to grab them and drag them under. If the water was shallow enough for even Sans to make out the bottom, then such beasts simply wouldn’t fit in this part of Waterfall. Even if they slept far up along the shoreline, that didn’t eliminate the risks from tentacles or telekinesis or similar. Best to just avoid the problem entirely.

It was around about then, as Sans was looking around at their makeshift campsite for the night, that Papyrus collapsed.

It was a slow, terrible collapse. Papyrus was very tall, and so he had a very long way to fall. First he tried to step, and then he failed. His legs bent and buckled, his knees hit the stone ground with an audible _clatter_. Then the rest of him pitched forward like a falling tree. Sans winced at the faint, sickening _crunch_ his cracked ribs made on impact. He wanted to try and stop the fall. Later on, he would kick himself over and over again for only moving in much too late to stop the fall. And later on, he would reflect on how just the simple horror of seeing Papyrus buckle and finally _break_ like that had kept him rooted to the spot.

But Papyrus made no other sound as he fell, and didn’t move once he was sprawled there on the ground. His brother was still and quiet, so much so that for a moment Sans feared the worst.

“papyrus…!” he cried, much too late, and stumbled to his brother’s side much too late. Only then did he see that his brother’s eyesockets were still open, the eyelights there still burning bright and distant and cold. Sans sighed with a relief so overwhelming that he felt dizzy from it.

“YES…” his brother murmured, sounding strangely thoughtful. As though he hadn’t just fallen. “YES, THIS SPOT WILL DO NICELY.”

Without any further prompting – he was not incapable of doing small things right, at least – Sans went to work untying or unhooking the other two packs from Papyrus. He set them safely against the wall, and then went rummaging through one to see what food they’d been left. “you need to eat something,” he babbled. “you need to get your hp back up, i can’t…”

His voice wavered traitorously. Sans went still, his hands curled around the wrappings of what might have been a cheeseburger beneath. Papyrus hated cheeseburgers. Sans loved them.

“…i can’t heal you.”

It was a skill he’d wished for more times than Sans could remember. It was a skill he could never learn.

“I KNOW THAT,” said Papyrus, and Sans giggled a little hysterically at the note of faint reproach in his brother’s voice. The taller skeleton harrumphed in reply, and closed his eyesockets. “I’M TOO TIRED TO FORCE MYSELF TO EAT THE SLOP THAT WRETCHED ELEMENTAL SCORCHES UP. PERHAPS AFTER A SHORT NAP. _YOU_ , HOWEVER, WILL EAT SOMETHING. AND THEN KEEP WATCH, PERHAPS, IF YOU’RE ABSOLUTELY DESPERATE FOR A WAY TO MAKE YOURSELF USEFUL.”

“i think i really am,” Sans murmured quietly. A watch was probably a good idea, all things considered. So he nodded before realizing that his brother couldn’t see. “okay. sleep tight, bro.”

“…EAT WELL, SANS.”

Then Papyrus let out a faint sigh, and was still and quiet from there. After a while, though, he settled enough into sleep that he started rattling faintly. That was normal, though. His brother had always been a somewhat restless sleeper, and so Sans found the sound soothing.

Sans settled back against the wall, near enough to his brother to hopefully keep watch while still being far enough away that he wouldn’t disturb Papyrus with the sounds of eating. Then he unwrapped the burger and took an enormous bite. Once the taste passed his teeth, it was all Sans could do not to moan aloud. It was even still a little warm. In that moment, trading a house for this food seemed like the most generous possible trade in the world.

He was pretty sure that the first bite did the trick of boosting his HP back up. Sans took his time eating the rest of it, though, just in case. It was only when he was scraping ketchup off his fingerbones with his teeth that he really thought back to the elemental, and Sans felt his soul twinge with regret. Grillby had always been at least a sort of friend, to Sans – certainly more than Papyrus had been for most of their lives. Only in that moment did it sink in that Sans would probably never see him again. Even assuming that the two of them didn’t die trying to meet up with Frisk again, never mind what happened from there, returning to Snowdin would be tantamount to suicide.

Sans knew that he couldn’t have stood to make any other choice. That didn’t mean he couldn’t regret that the choice had been necessary at all. There were good monsters in the Underground. Grillby was proof of that. It was hatred and fear and a twisted, broken history that forced them to keep their heads down. And it all stemmed from Asgore. It all started with Asgore.

Sans glanced at his brother, then. Papyrus was sleeping fitfully, but he was sleeping and hopefully that would help. Irrational and emotional as it was, Sans wanted to go to his brother, to maybe try and soothe whatever bad dreams he had. He knew better, though. He knew what a risk it would be for him. All it would take would be Papyrus lashing out at the wrong moment, even if he didn’t know he was doing it.

Now that he’d actually gotten out of Snowdin, Sans didn’t fancy dying today. So with a tired soul, he simply crumpled up the empty burger wrapping, tossed it in a random direction, and settled back against the wall.

*  *  *

Sans awoke with a start, to the sound of faint singing. _“Si Re Si Mi Si Mi Mi Mi…”_

And then the humming stopped abruptly, as whatever was approaching realized that he was awake. Sans did not, however, hear the sound of the intruder moving away. In fact, after a pause that seemed to last an eternity, he heard the wet, scraping sound of slimy flesh being dragged over rock – closer, _closer_ …

He strained his vision against the darkness. Sans made out a faint light down the path, drawing steadily nearer. It was a beautiful glow, really – like what he imagined a star might look like, or as though one of the gemstones that dotted the ceiling deep within Waterfall had fallen down. He was seized with an overpowering urge to go investigate.

Then the part of his mind that had survived the escape from Snowdin and countess years of sentry duty in the teenager-infested forest told him why the light looked so strange. Why there seemed to be two sources of it, in fact.

This was because the beautiful starry light was reflecting off two jagged rows of long, needle-sharp teeth.

Frantically, suddenly alert and alive as it ever was, his mind raced to take in other details. As the monster drew nearer, Sans could see that it looked small, smaller even than him. He squinted, trying to *CHECK it, but at this distance, all he could guess was that it definitely had more HP than he did right now, and possibly had more than Papyrus had left. It _probably_ wasn’t stronger than his brother at his best, though it felt as though it was close. Besides, Papyrus wasn’t at his best. Depending on the tricks the monster had up its metaphorical sleeve, even Papyrus might have a fight on his hands.

Sans had to act now. That was the one outcome he kept coming back to, as the stranger dragged itself nearer, nearer. He was at maximum HP, pathetic as his maximum levels were. He _could_ fight, much as he hated it.

He didn’t fancy dying here today.

He wasn’t going to lose his brother after all of this.

Sans got slowly to his feet. He hoped it made him look cool and confident, and not like he was having to make a conscious effort to keep his knees from rattling. “what do you want?” he asked, and at least his voice was mostly steady.

The monster stopped approaching. Now it was near enough for Sans to see the lights reflecting off its eyes, as well as its teeth. It opened its mouth and clicked its teeth as though to say something, but all that emerged was a disjointed fragment of song that trailed away to a hiss. It tried to drag itself nearer. Sans jerked his hands up into the air and raised a wall of bones in its path – more to make a point, than because he thought it would actually stop the stranger.

“we don’t have to fight.”

The fish monster _hissed_ violently, before vaulting itself up into the air, there to hover up above the wall. Sans gritted his teeth, reached out, and tried to turn its soul blue. Even as he got a grip, he felt a torrent of magical bullets pouring forth from its soul towards his.

Those, at least, were easy for him to dodge. One-on-one, Sans always had some tricks he could fall back on. He still really, truly didn’t want to gain any execution points, though – it was a point of pride, and Sans had few enough of those. So he asked again: “what do you want? i asked you pretty nicely before, under the circumstances. ‘sides, i don’t really have a lot of patience to _fish_ that answer out of ya if you won’t give it to me.”

The monster hissed loudly again, and tried to launch itself at him. Sans considered simply dodging, but remembered his brother beside him at the last minute. So he reaffirmed his grip on the creature’s soul, and jerked her forcibly into the shallow lake to his left. He tried to do it carefully, but there was still an unpleasantly impactful sort of sound as it struck the bottom.

Sans waited, and he hoped. He hoped that was enough, please let it be enough just this once…

Even when the monster surfaced again, he kept his jaw clenched tight with hoping. When the fish monster opened its mouth, Sans braced himself…

But only ordinary notes poured for this time, mournful and sad enough to make his soul ache in sympathy. _“Si Re Si Mi Si Hungry Hungry Hungry…”_

“…hungry?” He scarcely dared to believe what he was hearing. “you’re _hungry_? is _that_ what this is all about?” He couldn’t help but laugh aloud with relief. Had asking nicely really done the trick, just this once? “well, _come on_.” Still grinning, he motioned the creature over. “we’ve got some food that’s _way_ tastier than a couple of skeletons would be.”

Slowly, seeming so very cautious now, the strange monster rose up from the lake, yet again hovering midair. It tilted its head in a way that seemed curious, at least. It was hard to tell when the monster seemed to be mostly head.

Sans spread his arms wide and motioned it nearer. “come on,” he said gently. “if you’re really just hungry, come on.” He winked broadly at his newfound dinner guest. “let’s chew the fat. my brother and i are new in town.”

In the solitary light dangling from its head, the monster’s teeth rearranged itself in what might have been a smile. So Sans took the risk of turning his back to go digging in his pack for another burger. It was a risk that didn’t result in him being dusted on the spot.

It was only once the strangely shy monster was munching happily away on another one of Grillby’s burgers that Sans realized that Papyrus hadn’t woken up yet. Of course, it had been a relatively quiet and mercifully brief fight between him and the newcomer, but his brother’s long and brutal reign as leader of Snowdin’s Royal Guard meant that he usually had better instincts and much better reflexes than this.

Sans left his new friend to eat, and went to check on his brother. He lifted an eyesocket to confirm that the lights were still on, checked the soul to make sure that it wasn’t about to break. They were and it wasn’t. Papyrus really was just that exhausted.

Sans made an executive decision, and shook him awake. “bro, c’mon. breakfast time.”

“NO,” Papyrus grumbled immediately, trying to turn over onto his other side and away from Sans. He twitched violently as he did so, stifling a guttural growl of pain. Sans felt his soul ache anew with sympathy. He moved around to face Papyrus once more, and offered a hand.

“yes,” he said, gently. “c’mon, papyrus. time to put that iron stomach to good use.”

Papyrus glowered up at him for a moment. Then he reached out, carefully took Sans’ hand, and allowed himself to be pulled into a sitting position. Doing so let him spot the stranger still tearing into its burger. His brother’s eyesockets immediately narrowed, he raised a hand in a gesture Sans recognized as the beginnings of trying to summon a bone to attack with. Moving faster than he ever did when he wasn’t under attack, Sans reached out to grab Papyrus’ wrist.

“this is my new friend,” he said hastily. He glanced over at the monster and squinted, trying to take a closer look now that he was no longer in immediate danger. “she…?” The stranger nodded. “yeah. she was just kinda hungry. thought i’d share, y’know?”

Papyrus glowered at the other monster, obviously not in favor of Sans’ plan. But Sans also thought he could guess, by the look on his brother’s face, that Papyrus also guessed that it hadn’t been quite as simple as that, that Sans had made the best decision he thought possible in rather pressured circumstances. So he said nothing, just accepted another burger and dug into it so ferociously that Sans was certain he saw a few scraps of paper come away in Papyrus’ teeth. With his new friend and his brother thusly accounted for, Sans settled down to finish his own meal, too.

And so they passed a relatively peaceful while together, all three of them. When the monster who had barely an hour ago tried to eat them finished eating, she pulled herself industriously across the ground and over to Sans. He felt Papyrus brace himself to attack, and personally braced himself to dodge out of the way, but otherwise let her come.

When she was near enough to reach out and touch him, that was all she did – she patted his knee with a fin, and stretched her mouth in a long, toothy smile that seemed to glow in the light of her headlamp.

_“Shyren.”_

Sans blinked, stared…and then smiled, as comprehension dawned. “yeah? great to meet ya, shyren. the name’s sans.” He tapped her fin carefully with his hand. “gimme, uh…one?”

She made a hoarse, rasping sort of sound that he let himself believe was a laugh. Then she ducked her head, waved a fin at him, and turned to head back towards the shallow lake. After a moment, Papyrus let out a huff of impatience, got to his feet, and picked her up bodily. Sans’ soul stuttered with a flash of dread, and he saw Shyren tense, but Papyrus merely dropped her in the water and returned to his seat.

“I HOPE YOU KNOW OUR SUPPLIES WON’T LAST FOREVER,” was the first thing he said as he sat down again.

Sans gave a little half-shrug. “sure i do. i hope you know that we can’t fight our way through _every_ monster that might try to take a bite out of us here.”

“MAYBE _YOU_ COULDN’T.”

“i know _i_ couldn’t. and it’d be great if i didn’t have to try. y’know?”

“YOU THINK I COULDN’T PROTECT US BOTH, SANS?”

Sans closed his mouth against the expected reply, frowning faintly. Just when he thought he had their new situation figured out, his brother went and said something like _that_. It wasn’t bad, to hear such unexpected things, not as such. It just reinforced the idea that he really was out of his depth and traveling without a map, now. The brutal rules of the Underground really were something he was leaving far behind him.

Maybe Papyrus felt the same. He remembered their conversation back on the road, before all of this had happened, when Frisk had been there to hear it. Maybe Papyrus had always felt the same, and was remembering how to say it. Sans hoped so. He hoped he could be the sort of brother that helped Papyrus remember.

He hoped he could avoid messing everything up, the way he so often did. Papyrus was important. Papyrus was loud, spiky, possessive, fierce, protective, _important_.

“i know you could, bro. if you had to. but…that doesn’t mean you have to. i wanna help, too, y’know?” He hesitated, and then reached out across the distance between them to pat Papyrus on the shoulder. “we’re in this together. right?”

There was a long, long pause in which the very mountain itself seemed to hold its breath.

Then Papyrus nodded, and patted Sans’ hand with the one he had remaining.

“I SUPPOSE,” he huffed, and Sans grinned in relief.


	3. Don't Give Up

It was a long trek through Waterfall, and not every monster they met along the way was as easily bribed as Shyren. Some were, though. Some were vicious and mean and territorial as anything, but some were just hungry and Grillby really had packed them a lot of food. Maybe he’d seen this coming. No one had ever really known the bartender’s story before he’d turned up in the bar, but theoretically he must have passed through Waterfall to get to Snowdin, right?

Occasionally, Sans still experienced a pang at the thought that he might never know. He always tried to set it aside and use the energy to keep moving, instead.

And it was slow going, there was no denying or avoiding that much. Sans could take shortcuts from island to island, but Papyrus’ ability to swim had been badly hampered by the loss of his arm. Sans could see him struggling to learn to compensate for it, but he was having to learn as they went. There was also the matter of protecting their supplies, which oftentimes necessitated long detours in search of shallow fords.

But they made progress. They made it in fits and starts, but they kept going forward. And they left behind them at least a few monsters who were less hungry after meeting the brothers than before. Even Papyrus stopped grumbling about that eventually. Maybe he just didn’t see the point in continuing to fuss, in the face of something that made Sans feel as determined as he ever was.

Their supply level was still a near thing, and it was a thing that nearly ran out before they made it to Hotland. It had to have been at least a week later, and the skeletons made camp beneath the glowing neon sign announcing it at long last. Papyrus immediately stretched out for a nap so that Sans wouldn’t comment on the way he was shaking from exhaustion. Sans didn’t comment, and instead went digging through the three haversacks to find out what they might have left for dinner.

His fingerbones brushed against a piece of paper that was folded rather differently than the sort that had so far wrapped all their burgers and fries. Frowning curiously, Sans drew it carefully out into the reddened light to read. He unfolded it, and Grillby’s impossibly neat handwriting met his eyelights.

It was a note. It was a perfunctory and short one, but it was still something Grillby had thought he’d live long enough to read. Sans was frankly flattered for his old friend’s confidence. 

_Take care of yourself, Sans. The way things are going, maybe I’ll be following you one day, soon._

_And don’t think you’re getting out of your tab just because you finally skipped town._

_-G_

“wouldn’t dream of it, pal,” Sans murmured fondly. He folded the note up carefully once more, and tucked it into a pocket of his coat as a precious treasure. “wouldn’t dream of it.”

There was a warm little light in his soul as he kept watch, which had nothing to do with the harsh red light of Hotland at the end of the tunnel.

He didn’t mention the note when Papyrus woke up. If Papyrus noticed the quicker pace in his step as they set off again, he only nodded approvingly and didn’t comment. Maybe he just attributed it to the fact that their haversacks were definitely lighter.

“WE SHOULD HAVE FOUND THE HUMAN BY NOW.”

“you think? they got a good head start over us.”

“AND WHAT USE COULD THEY HAVE MADE OF THAT HEAD START, IN A PLACE LIKE WATERFALL? FOR IT TO HAVE SLOWED _US_ DOWN THAT BADLY, I HATE TO THINK WHAT MIGHT HAVE HAPPENED TO SUCH A WEAK CHILD.”

Sans thought back to how Frisk had stared Papyrus down – they’d done it with tears in their eyes, but they had stared him down. He thought back to Shyren, placated from a bloodthirsty rampage by a cheeseburger. “you really still think they’re weak, bro?”

Papyrus moved as if to fold his arms across his chest, and grimaced as he realized he’d given in to force of habit. He bunched his fist at his side, instead. “KILL OR BE KILLED.”

“i don’t believe that.” He believed it now less than ever. Papyrus still didn’t look entirely convinced, however, and so Sans asked another question that was weighing on him. “so if you don’t think we’re gonna find ‘em, what are you coming to hotland with me for?”

“I AM _NOT_ GOING TO HOTLAND. I AM _GOING_ TO NEW HOME.”

“why?”

After everything that had happened over the past several days, even Sans could no longer believe that Papyrus meant him harm or intended to betray him. Not even when Papyrus replied with a harrumph, and especially not when he carried on to say: “I AM GOING TO KILL KING ASGORE, OF COURSE.”

It was quite a grand and dramatic declaration, which made it even more embarrassing when Sans broke out into a fit of shocked, disbelieving laughter. The taller skeleton let out a growl and stamped his foot. “AND _WHAT_ , MAY I ASK, IS SO FUNNY?”

“…you mean you’re serious?”

“OF _COURSE_ I AM SERIOUS! I AM _ALWAYS_ SERIOUS! AND I THOUGHT, SANS, THAT THIS MIGHT BE ONE OPPORTUNITY WHERE YOU WOULD BE SERIOUS WITH ME!” Papyrus jabbed a fingerbone at him. Sans had to fight the urge to shy away from it – it felt like an accusation, more than anything. “YOU SAID IT YOURSELF! THE UNDERGROUND NEEDS TO CHANGE! IT MADE US TWISTED AND LESSER THAN WHAT WE WERE ONCE, ON THE SURFACE.” His brother glowered fiercely down at the ground beneath their feet, and added in a tone as quiet as he ever managed: “IT DROVE US APART.”

“papyrus…”

“ _ASGORE_ MADE THE UNDERGROUND WHAT IT IS! ASGORE MADE THESE RULES! ASGORE HAS TURNED US INTO THE BEASTS THAT HUMANS ALWAYS BELIEVED US TO BE! THAT IS UNFORGIVEABLE, AND I WILL NOT FORGIVE IT. THE UNDERGROUND NEEDS A NEW RULER, AND I INTEND TO CLAIM THAT MANTLE FOR MYSELF.”

Sans stared up at his brother, filled with terror and awe and no longer able to tell the difference. He considered reminding Papyrus that he only had one arm. He wondered whether that would really make a difference. Right now, as his brother strode on straight and tall despite his lingering wounds, he really did look like he could take on a god.

“i think,” Sans said instead. “that you would make a pretty good king, papyrus.”

“…THANK YOU, SANS.”

“i just hope you appreciate how much of a _royal_ pain in our pelvises it’s gonna take to get you that far.”

He heard his brother grinding his teeth. “COMPARED TO SURVIVING YOUR HORRIBLE JOKES, _ANYTHING_ IS A WALK IN THE PARK.”

They chatted back and forth for a little while as they walked, and the cold blue glow of Waterfall faded into the harsher red glare of Hotland. The path rose and grew narrower, and the distant light of lava became visible far below. It was beautiful, in a way, in part because it was such a jarring change from days of swamps and slimy plants. He was so distracted by the sight that Sans didn’t realize that Papyrus had stopped until his brother reached forward and closed a vice-like grip around Sans’ shoulder, holding him back. Even then, Sans looked to Papyrus first for a sign as to why. His brother, meanwhile, was staring straight ahead with an expression as stony as the walls around them. At last, Sans looked ahead and saw why for himself.

He couldn’t remember the last time he’d seen Undyne without her armor. He couldn’t remember if he ever had. Papyrus had never talked much about his training with the head of the Royal Guard. Whenever Sans had asked, he’d simply said that he didn’t think Sans could stomach the details even without a stomach.

The fish monster stood tall and rigid without her armor now, however. She had removed it, piece-by-piece, and left each piece scattered carelessly around her feet. Undyne stood at the edge of the path, her helmet in her hands, staring down at the lava far, far below. Sans thought she looked…rather thoughtful. At least as far as he could tell on a face he’d so scarcely seen without the helmet on.

He could feel the conflict raging in Papyrus’ soul, though he could only guess at which side was which. When his brother spoke, all he said was: “UNDYNE.”

She whirled around sharply to face them. Clearly acting entirely on instinct, she let the helmet fall and summoned a glowing blue spear to her hand instead. The helmet itself rolled across the ground from the impact, and teetered precariously on the edge of the road when it stopped. Papyrus, meanwhile, reacted by settling into a fighting stance of his own, summoning a long bone to the only hand he had left. Sans took his silent cue to get more securely behind his brother, thought he also stayed braced to back him up.

The universe seemed to hold its breath. When it let it all out in a sigh, it was Undyne who gave ground first. She lowered her hand, let the spear fade, and looked away.

“What are you both doing here? Have you come to watch?”

Papyrus let out a derisive huff. “ARROGANCE. WHAT MAKES YOU THINK WE CAME HERE FOR YOU IN THE FIRST PLACE?”

“So you’re looking for the human? Is that it?”

Papyrus went still which shock. Sans, meanwhile, felt his soul lift higher with hope. “you’ve seen them?”

The other warrior let out a harsh bark of laughter. “ _Seen_ them? I haven’t just seen them, I’ve completely failed to kill them!” She gestured contemptuously down at her disassembled armor, then jerked a thumb over her shoulder, towards Hotland. Neither skeleton asked. Sans wasn’t even sure he wanted to know. But the story came tumbling out of Undyne like falling water anyway. Perhaps that was the only way it wouldn’t drown her.

“I chased them down. I chased them until I couldn’t take another step in this damn heat. When I collapsed, all I knew was that I was at their mercy. All I knew what that I had failed, and that it was a deserved end for me as a result.”

Her fists clenched tightly enough to shake. Sans _saw_ the shout bubbling up inside her soul, saw her draw in a deep breath and throw her head back and _roar_ the injustice of it to the heavens beyond the mountain: _“They brought me water!”_

She slumped back, panting, one hand pressed over her face. Sans watched her quietly, no possible idea of what to say. Even Papyrus seemed to be at a loss.

At last, Undyne carried on, bitterness in her smile and all but dripping from her voice. “They brought me water. My greatest enemy, looking at me like I was as pitiable as a child. They even waited until I got back up. They were so… _polite_.” She spat the word, and then all in a rush the fight she’d mustered seemed to leave her. She turned away from them both once more, staring down into the lava with a look that Sans now recognized as one of _longing_. “What’s left for me, now? Have you both come to watch? Great. It’ll all be over soon.”

“I THOUGHT THE SAME,” Papyrus said all of a sudden. “WHEN THE HUMAN DEFEATED ME.”

Undyne snorted derisively, and pointed at the empty socket where his arm used to be. “At least you actually made them put up a fight. I mean, _damn_.”

“ _THIS_ WAS NOT THEIR DOING. THEY DEFEATED ME WITHOUT EVER RAISING A HAND. THEY DEFEATED ME BY MAKING IT SEEM AS THOUGH IT WAS POINTLESS TO FIGHT AT ALL. BY QUESTIONING EVERYTHING I HAD EVER GROWN TO UNDERSTAND. SOUND FAMILIAR?”

Undyne’s remaining eye had gone wide and wary. She nodded, slowly.

“SO I QUESTIONED, AND I FOUND A NEW ANSWER.” Papyrus drew himself up to his full height, jutting out his chin defiantly as he declared himself. “THAT ANSWER IS TO BURN DOWN EVERYTHING I THOUGHT I KNEW, AND REBUILD IT BY ANY MEANS NECESSARY. SURELY YOU SEE NOW, UNDYNE, THAT THE UNDERGROUND IS STAGNANT AND BROKEN. WE HAVE LOST SIGHT OF OUR TRUE PURPOSE. WE HAVE LOST SIGHT OF WHO WE ARE.”

“We’re _monsters_ , Papyrus,” Undyne pointed out with a huff. “This is how it’s always been, and it’s gotten us this far.”

“WHAT DOES THAT MATTER? WE _ARE_ MONSTERS, AND WE SHOULD BE _BETTER THAN THEM_.”

That gave her pause. Undyne opened her mouth, and then closed it once more. Papyrus seemed satisfied by her willingness to listen, and carried on. “SO I WILL MAKE US BETTER, BY CARVING OUT WHAT HAS MADE US WORSE. AND…I WILL PROTECT THE HUMAN WHO SHOWED ME THAT THIS WAS THE WAY. YOU COULD DO WORSE THAN TO DO THE SAME. WE ARE GOING TO FIND THEM, UNDYNE. YOU CAN FOLLOW US…OR NOT.”

He started forward once more, and Sans had to give himself a little shake before he could bring himself to follow. Papyrus stalked past Undyne without looking at her. Sans couldn’t bring himself to do that much. He slowed down as he passed her by, and offered her a hopeful sort of smile.

“it hasn’t been too bad, so far. they’re a pretty great kid, once you get to know them.”

And he didn’t want to keep going. He didn’t want to leave her in case she really did decide to give up. But when Papyrus barked out his name, Sans did turn away and hasten to catch up with his brother. Just as well, perhaps – he was too much of a coward to see whether his words would make a difference or only make things worse. Probably the latter. It had really been Frisk’s words that had swayed Papyrus’ soul. Sans had only ever just bought them time to say them.

As they walked along together down the road, Sans waited for the sound of a body falling. He waited for a distant splash.

It never came.

Footsteps came, however, approaching at increasingly greater speed. And Sans ducked his head to hide a smile.

“It’s a long way to New Home,” Undyne said, slinging an arm around Papyrus’ shoulder without missing a beat. “Maybe Dr. Alphys can find us a shortcut.”

**Notes for the Chapter:**

> I hope it goes without saying, but if you ever have a friend who's suicidal, for the love of all that is holy don't treat them like Papyrus treated Undyne here. He meant well and was trying his best, it was still a marked improvement over how he might have handled the situation before meeting Frisk, but...yeah. Don't do that. 
> 
> Otherwise, here we are at the end! I always feel weird about separating fics of this length into chapters. I'm hardly against long oneshots, it's just that a 10k+ oneshot seemed a bit excessive. I gotta say, I did not expect this fic to ever come about. And it was not an easy fic to write. But now that it's done, I'm really glad I wrote it. It was nice, getting to explore more of this interpretation of Sans and Papyrus (and give them a nudge towards being the kind of brothers we all know they can be). Given how long it took me to write this fic, I'm not sure if my ideas for future sequels will ever come to fruition. But the ideas are definitely there, and that's been a pleasant surprise to me. Before "Line in the Snow", Underfell in general as an AU was never something that caught my attention. So this has been a journey for me as well as all of you. 
> 
> Thank you for reading.


End file.
